CONCERTED EVOLUTION OF MAMMALIAN CARDIAC MYOSIN HEAVY-CHAIN GENES

We have recently determined the complete nucleotide sequences of the c ardiac alpha- and beta-myosin heavy chain (MyHC) genes from both human and Syrian hamster. These genomic sequence data were used to study th e molecular evolution of the cardiac MyHC genes. Between the alpha- an d beta-MyHC genes, multiple gene conversion events were detected by (1 ) maximum parsimony tree analyses, (2) synonymous substitution analyse s, and (3) detection of pairwise identity of intron sequences. Approxi mately half of the 40 cardiac MyHC exons have undergone concerted evol ution through the process of gene conversion with the other half under going divergent evolution. Gene conversion occurred more often in exon s encoding the alpha-helical myosin rod domain than in the globular he ad domain, and an apparent directional bias was also observed, with tr ansfer of-genetic material occurring more often from beta to alpha.